Control arrangements for mine roof support props

ABSTRACT

A control arrangement for a mine roof support prop which arrangement has a setting valve which can connect the working chamber of the prop to a pressure fluid source to extend the prop or to a storage vessel to retract the prop. A further valve device incorporates a slide valve which is automatically moved against the force of a spring when the prop is set and the pressure in the working chamber reaches the pressure of the source to connect a further pressure fluid source to the working chamber. The further source supplies fluid at a higher pressure than the first source and the valve device has a further spring-loaded slide valve which opens to effect closure of the first slide valve when the pressure in the working chamber reaches the pressure of the further source.

Umted States Patent [1 1 [111 Behrens et al. [451 Dec. 4, 1973 [54] CONTROL ARRANGEMENTS FOR MINE 1,428,998 9/1922 Trace 91/29 R SUPPORT PROPS 1,805,367 5/ 1931 King 91/29 2,391,930 1/1946 Stone 91/29 Inventors: Volker Behrens,

Dortmund-Schamhorst; Walter Weirich, Dortmund; Harry Rosenberg, Ludinghausen, all of Germany Gewerkschaft Eisenhutte Westfalia, Westfalia, Germany Filed: Sept. 15, 1972 Appl. No.: 289,711

Assignee:

Foreign Application Priority Data Sept. 17, 1971 Germany P 21 46 502.1

U.S. Cl. 91 29, 91 /451 Int. Cl. FlSb 13/042 Field of Search 91/29, 2 451;

References Cited UNITED STATES PATENTS 7/1914 Clark 91/29 Primary Examiner-Paul E. Maslousky Attorney-Richard C. Sughrue et a1.

[57] ABSTRACT A control arrangement for a mine roof support prop which arrangement has a setting valve which can connect the working chamber of the prop to a pressure fluid source to extend the prop or to a storage vessel to retract the prop. A further valve device incorporates a slide valve which is automatically moved against the force of a spring when the prop is set and the pressure in the working chamber reaches the pressure of the source to connect a further pressure fluid source to the working chamber.

The further source supplies fluid at a higher pressure than the first source and the valve device has a further spring-loaded slide valve which opens to effect closure of the first slide valve when the pressure in the working chamber reaches the pressure of the further source 14 Claims, 2 Drawing Figures CONTROL ARRANGEMENTS FOR MINE ROOF SUPPORT PROPS BACKGROUND TO THE INVENTION The present invention relates to a control arrangement for use with mine roof support props and to a valve device usable in such an arrangement.

In the mining art it is generally desirable that individual mine roof support props, or groups of props forming part of a movable support frame, be controlled so that the props are set against the roof with a uniform pressure as high as possible. The pressure of hydraulic fluid in mine workings, which supplies various other devices, is however not sufficiently high to enable the desired high prop setting loads to be obtained; It is not feasible to increase the pressure of the fluid since these other devices would need extensive modification to work at higher pressure and this-would involve considerable cost. Alsoan overall increase in the pressure of the working fluid would not necessarily provide uniform setting loads for the props since the prevailingworking pressure experienced by each prop is liable to vary. It is known to incorporate setting valves in the control arrangement for supplying fluid to the props. By ensuring that the setting valves remain open for acertain period of time after the roof cap contacts the roof before then closing the setting load can be made ashigh as possible. This time-dependent opening of the setting valves is not however satisfactory and in many cases props are still set with an inadequate load. In other arrangements extensive supervision by an operator is necessary to ensure the props have high setting loads.

A general object of this invention is to provide an improved control arrangement and valve device for use with a mine roof support prop.

SUMMARY OF THE INVENTION According to the invention there is provided a control arrangement for use with a mineral mining installation with a mine roof support prop and first and second pressure fluid sources for supplying fluid to the working chamber of saidprop; said arrangement including avalve device adapted in use to connect said first source to the working chamber when the pressure in said chamber reaches a pre-determined first value and to disconnect said first source from said chamber when the pressure in said chamber reaches a pre-determined second value greater than that of said first value.

In another aspect the invention providesa control arrangementfor use with a mine roof support prop; said arrangement comprising a first pressure fluid source connectible to the working chamber of the mine roof support prop, a second pressure fluid source connectible to said working chamber and a valve device operably disposed between said first source and the working chamber and adapted to connect said first source to said working chamber when the pressure in said chamber reaches a pre-determinedfirst value and to disconnect said first source from said chamber when the pressure in the said chamber reaches a pre-determined second value greater than that of said first value. The invention also provides for use in such a control arrangement a valve device with a multi-part housing, a bore connectible to the working chamber of the prop which receives pressure fluid from a first pressure fluid source, a further bore connectible to a second pressure 2 fluid source for supplying fluid at greater pressure than said first source, a valve in the form of a slide with a piston surface adapted to be contacted by pressure fluidin said bore, the slide being disposed to move to con nect or disconnect the further bore from said bore, a

spring biasing the slide to a position where the further bore is disconnected from said bore whereby the slide moves against the force of the spring to connect the further bore to said bore when a first pre-determined pressure prevails in saidbore, a further piston surface fluid to the prop workingchamber so that the prop extends. When the prop sets against the roof the pressure in the working. chamber rises to that of the second source, i.e. the first value, and at this stage the valve device operates to connect the first source to the working chamber. When the pressure in the working chamber rises to that of the first source i.e. the second value, the

valve device operates to disconnect the first source from the working chamber leaving the prop set with the pressure in the working chamber nominally at the pressure of the first source. It isadvisable to connect a'pressure-relief valve to the working chamber to'enable outflow of fluid should'the roof load increase to raise the pressure in the chamber beyond a safe limit. The control arrangement thus enables the prop to be set with a setting load higher than the nominal working pressure of the fluid supplied by the second source which would normally supply the various other devicesin the mine working.

Preferably the spring-loaded valve of the valve device is in the form of a further slide adapted to move within an axial bore in said slide.

The further piston surface in the device can be formed by an abutment piece having a recess receiving a shaped; head of the slide and contacting said spring.

The further slide may extend through the shaped head of the slide into the chamber of the device. The further slide then preferably has a blind axial bore communicating with at least one radial bore extending through the peripheral surface of the further slide and with said bore viathe interior of the slide.

The further slide may also have a shaped'head which engages in a recess of a further abutment piece contacted by the spring associated with the further slide.

A non-retum valve may be located in a bore communicating with said chamber, said non-retum valve serving to allow fluid to flow outwardly from the chamber when the working chamber of the'prop is relieved and the pressure in the bore falls.

The invention may be understood more readily and various other features of the invention may become more apparent from consideration of the following description.

BRIEF DESCRIPTION OF DRAWINGS An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic diagram illustrating a hydraulic control arrangement made in accordance with the invention; and

FIG. 2 is a sectional side view of a valve device usable in the control arrangement.

DESCRIPTION OF PREFERRED EMBODIMENT Referring initially to FIG. 1, there is shown a control arrangement for controlling the operation of a hydraulically operated prop 11. The arrangement utilizes, inter alia, a change over setting valve 10 which can itself be operated automatically or manually. The valve 10 has a first port connected via a conduit 12 to the working chamber 13 of the prop 11 facing a piston 14 in known manner. The valve 10 also has an inlet port connected to a source of pressure fluid P1 and a further port connected via a return conduit 16 to a pressure fluid storage vessel. The valve 10 may be operated to connect the source P1 to the conduit 12 and the chamber 13 via a non-return valve to thereby set the prop 11 or to connect the conduit 12 to the return conduit 16 to thereby relieve the prop 11. During normal conditions the working pressure in the conduit 12 would be, for example, 300 atmospheres excess pressure, i.e. P1. The conduit 12 is also connected through a springloaded pressure relief valve 15 to the return conduit 16. The valve 15 is designed to open when the load on the prop 11 increases to a pre-determined level thereby decreasing the pressure in the chamber 13. Where the working pressure is 300 atmospheres excess pressure the valve 15 is designed to open, for example, at about 450 atmospheres excess pressure. I

In accordance with the invention, a further valve 17 has an outlet port connected to the conduit 12 leading to the chamber 13. The valve 17 has an inlet port connected via a non-return valve and a conduit 19 to a second pressure fluid source P2 which supplies fluid at greater pressure than the source P1. Where the source P1 supplies fluid at a working pressure of 300 atmospheres excess pressure the source P2 would, for example, supply fluid at a working pressure of about 400 atmospheres excess pressure. The valve 17 is operated by a member, preferably a slide, which is biased by a spring 18 into a closed position where connection between the conduits 19, 12 is blocked. The operating member is activated by pistons 20, 21 acting in opposition to one another. The piston 20 opposes the action of the spring 18 and tends to open the valve to establish communication between the conduits 12, 19 whereas the piston 21 supplements the spring 18 and tends to close the valve and block communication between the conduits 19, 12.

The piston 20 is fed via a conduit 22 which connects with the working conduit 12 and the piston 21 is connected via conduits 23, 8 to a pressure operated springloaded valve 24 connected in turn via a conduit 25 t the conduit 12. A valve 24 is designed to open and establish communication between the conduits 23, 12 when a pressure of about 400 atmospheres excess pressure, i.e. P2, prevails in the conduit 12 and the chamber 13. A non-return valve 26 is connected between the conduits 25, 23.

The operation of the arrangement is as follows:

If the change-over valve is operated to connect the source P1 to the chamber 13 of the prop 11 via the conduit 12 the piston 14 of the prop 11 will move so that the prop 11 will extend and become set against the roof of the pertinent mine working. When the roof cap carried by the prop 11 actually contacts the roof the pressure in the chamber 13 will rise to about 300 atmospheres excess pressure, i.e. P1, and this pressure acts upon the piston 20 of the valve 17 to open the valve 17 in opposition to the force of the spring 18. When the valve 17 opens to establish communication between the conduits 19, 12 the chamber 13 is charged with additional fluid from the source P2 until the pressure in the chamber 13 reaches 400 atmospheres excess pressure, i.e. P2. When this pressure prevails in the chamber 13 and the conduit 12 the valve 24 opens to subject the piston 21 to this pressure.

The slide of the valve 17 now moves back to close the valve 17 and block communication between the conduits l2, 19. The source P2 thus supplies sufiicient fluid to raise the pressure in the chamber 13 to the pressure of the source P2. If for any reason, such as an increase in the roof loading, the pressure in the chamber 13 should rise still further the valve 15 may be operated to reduce the pressure in the chamber 13.

When the prop 11 is to be relieved and retracted the valve 10 is operated to connect the chamber 13 and the conduit 12 to the return conduit 16. The fluid in the pertinent operating chamber of the piston 21 will at this stage be removed via the valve 26 and the conduit 25, 16.

It is preferable to provide a composite valve device in the form of a cartridge-like structure combining the components enclosed in dot-dash lines in FIG. 1. An example of such a device is shown in FIG. 2. As shown in FIG. 2, the device is composed of a housing 30 partly receiving a body 31. The housing 30 and the body 31 are provided with complementary screw threads enabling these parts to be disassembled. The housing 30 is accomodated in a stepped part-threaded bore in a mounting block 32 which may form part of a control unit carried by a roof support frame or the like. The housing 30 is retained in the block 32 with the aid of a sleeve 33 screwed into the stepped bore. Within the body 31 is a central bore receiving a spool or slide 34. Sealing rings 35 are provided in grooves in the slide 34 to seat against the surface of the bore. The slide 34 has.

a part-spherical head 36 at its upper end. This head 36 locates in a correspondingly-shaped recess of an abutment piece 37. The abutment piece 37 is located in a chamber 40 in the housing 30 and above the body 31. The abutment piece 37 has a shoulder which bears the lower end of a compression spring 39. The upper end of the spring 39 engages a stop member 38 insertable into the interior of the housing 30. A retaining sleeve 57 is screwed into the upper end of the housing 30 to retain the member 38.

A radial bore 41 in the body 31 adjoins a groove 42 in the central bore accommodating the slide 34 and a longitudinal bore or port 43 communicates with the lower surface 44 of the slide 34. A further axial bore 45 in the body 31 extends between the chamber 40 and the port 43 and a non-return valve 46 is located in the stop member 38. The slide 48 has a part spherical head 50 which locates in a correspondingly shaped recess of an abutment piece 49, located within the member 38. The abutment piece 49 has a shoulder which bears the lower end of a compression spring 51, the upper end of the spring 51 engages a plug 52 screwed into the chamber 38. A sealing ring 53 is located in a groove in the end wall of the member 38 to seat against the outer face of the slide 48 and similarly a sealing ring 54 is located in a groove in the head 36 of the slide 34 to seat against the outer face of the slide 48. Sealing rings are also located in grooves in the body 31 and the member 38 to seat against the internal face of the outer wall of the housing 30. The slide 48 has a blind axial bore 55 leading inwardly from its lower end and this bore 55 communicates with radialbores 56 extending to the outer peripheral surface of the slide 48.

The valve constituted by the slide 34 represents the basic valve 17 in FIG. 1, the valve 46 represents the valve 26 in FIG. 1 and the valve constituted by the slide 48 represents the valve 24 in FIG. 1.

The lower face 44 of the slide 34 corresponds to the piston in FIG. 1, the upper face of the member 37 corresponds to the piston 21 in FIG. 1 and the spring 39 corresponds to the spring 18 in FIG. 1. One or both slides 34, 48 may be connected to a pin or similar device visible from the exterior of the device so that an operator can determine the operative position of the slide or slides. The pressures at which the slides 34, 48 respond can be adjusted by rotating the sleeve 57.

The operation of the device is as follows:

The bore 43 is connected to the conduit 22, 12 in FIG. 1 and the bore 41 is connected to the conduit 19 in FIG. 1. When the pressure in the bore 43 reaches the working pressure P1 the slide 34 moves upwardly against the force of the spring 39 so that the bore 41 communicates with the bore 43. When the pressure in the bores 43, 41, 47 reaches P2 the slide 48 moves upwardly against the force of the spring 51 until communication is established between the bore 47 and the chamber 40 via the bores 55, 56. Fluid flows into the chamber 40 to act on the upper face of the member 37, which serves as a differential piston. The slide 34 now moves downwardly to close communication between the bores 41, 43. If, as mentioned previously, the prop 11 of FIG. 1 is to be relieved the prop chamber 13 is connected to the return conduit 16. In this case the fluid in the chamber 40 can flow out from the device via the valve 46. It may be desirable to connect a pressure relief valve to the chamber 40.

We claim:

1. In a control arrangement for use with a mine roof support prop; a first pressure fluid source, a second pressure fluid source, the first source serving to supply fluid at a greater pressure than said second source, means for selectively connecting said second source to a working chamber of said prop to effect extension of the prop and a valve device connected between the first source and the working chamber of said prop, said valve device including a fluid pressure sensitive valve which opens to connect the first source to the working chamber of said prop when the pressure in the chamber reaches a pre-determined first value and which closes to disconnect the first source from the working chamber when the pressure in the chamber reaches a predetermined second value greater than said first value.

2. In a control arrangement for use with a mine roof support prop and having first and econd pressure fluid sources for supplying fluid to a working chamber of the mine roof support prop; the improvement comprising valve means forv connecting said first source to the working chamber when the pressure in the chamber reaches a predetermined first value dependent on the normal settingof the prop after admission of fluid from the second source and for disconnecting said first source from said chamber when the pressure in the chamber reaches a pre-determined second value higher than that of said first value.

3. An arrangement according to claim 2, further comprising a setting valve for selectively connecting the second source to the working chamber to effect extension of the prop and for selectively connecting the working chamber to a storage vessel to effect retraction of the prop.

4. An arrangement according to claim 2, wherein said valve means includes a valve actuated by the pressure prevailing in the working chamber to connect and disconnect the first source from the chamber to thereby increase the working pressure in aid chamber when theprop is set.

5. An arrangement according to claim 4, wherein said valve is a slide subjected to the force of a spring and to the influence of fluid pressure on piston surfaces acting in opposition to one another.

6. An arrangement according to claim 5, wherein said valve means has a further spring-loaded valve which opens at said second pressure value to enable fluid to contact one of said piston surfaces to effect closure of the slide valve.

7. An arrangement according to claim 6, wherein the further spring-loaded valve is also a slide and the slides are provided in a common housing.

8. An arrangement according to claim 2, and further comprising a pressure-relief valve connected to the working chamber of the prop.

9. In or for a control arrangement for use with a mine roof support prop, a valve device with a multi-part housing, a bore connectible to a working chamber of the prop which receives pressure fluid from a first pres-. sure fluid source, a further bore connectible to a second pressure fluid source for supplying fluid at greater pressure than said first source, a valve in the form of a slide with a piston surface adapted to be contacted by pressure fluid in said bore, the slide being disposed to move to connect or disconnect the further bore from said bore, a spring biasing the slide to a position where the further bore is disconnected from said bore whereby the slide moves against the force of the spring to connect the further bore to said bore when a first pre-determined pressure prevails in said bore, a further piston surface disposed in a chamber and adapted, .when subjected to pressure fluid, to move said slide to said position and a further spring-loaded valve adapted to cause pressure fluid to flow from said bore to said chamber when a second pre-determined pressure greater than said first pre-determined pressure prevails in said bore.

10. A device according to claim 9, wherein the spring-loaded valve is in the form of a further slide adapted to move within an axial bore in said slide.

11. A device according to claim 10, wherein the further piston surface is formed by an abutment piece havfurther abutment piece contacted by the spring associated with the further slide.

14. A device according to claim 9, and further comprising a non-retum valve locating in a bore communicating with said chamber, said non-retum valve serving to allow fluid to flow outwardly from the chamber when the working chamber of the prop is relieved and the pressure in the bore falls.

i t t a: 

1. In a control arrangement for use with a mine roof support prop; a first pressure fluid source, a second pressure fluid source, the first source serving to supply fluid at a greater pressure than said second source, means for selectively connecting said second source to a working chamber of said prop to effect extension of the prop and a valve device connected between the first source and the working chamber of said prop, said valve device including a fluid pressure sensitive valve which opens to connect the first source to the working chamber of said prop when the pressure in the chamber reaches a predetermined first value and which closes to disconnect the first source from the working chamber when the pressure in the chamber reaches a pre-determined second value greater than said first value.
 2. In a control arrangement for use with a mine roof support prop and having first and econd pressure fluid sources for supplying fluid to a working chamber of the mine roof support prop; the improvement comprising valve means for connecting said first source to the working chamber when the pressure in the chamber reaches a predetermined first value dependent on the normal setting of the prop after admission of fluid from the second source and for disconnecting said first source from said chamber when the pressure in the chamber reaches a pre-determined second value higher than that of said first value.
 3. An arrangement according to claim 2, further comprising a setting valve for selectively connecting the second source to the working chamber to effect extension of the prop and for selectively connecting the working chamber to a storage vessel to effect retraction of the prop.
 4. An arrangement according to claim 2, wherein said valve means includes a valve actuated by the pressure prevailing in the working chamber to connect and disconnect the first source from the chamber to thereby increase the working pressure in aid chamber when the prop is set.
 5. An arrangement according to claim 4, wherein said valve is a slide subjected to the force of a spring and to the influence of fluid pressure on piston surfaces acting in opposition to one another.
 6. An arrangement according to claim 5, wherein said valve means has a further sPring-loaded valve which opens at said second pressure value to enable fluid to contact one of said piston surfaces to effect closure of the slide valve.
 7. An arrangement according to claim 6, wherein the further spring-loaded valve is also a slide and the slides are provided in a common housing.
 8. An arrangement according to claim 2, and further comprising a pressure-relief valve connected to the working chamber of the prop.
 9. In or for a control arrangement for use with a mine roof support prop, a valve device with a multi-part housing, a bore connectible to a working chamber of the prop which receives pressure fluid from a first pressure fluid source, a further bore connectible to a second pressure fluid source for supplying fluid at greater pressure than said first source, a valve in the form of a slide with a piston surface adapted to be contacted by pressure fluid in said bore, the slide being disposed to move to connect or disconnect the further bore from said bore, a spring biasing the slide to a position where the further bore is disconnected from said bore whereby the slide moves against the force of the spring to connect the further bore to said bore when a first pre-determined pressure prevails in said bore, a further piston surface disposed in a chamber and adapted, when subjected to pressure fluid, to move said slide to said position and a further spring-loaded valve adapted to cause pressure fluid to flow from said bore to said chamber when a second pre-determined pressure greater than said first pre-determined pressure prevails in said bore.
 10. A device according to claim 9, wherein the spring-loaded valve is in the form of a further slide adapted to move within an axial bore in said slide.
 11. A device according to claim 10, wherein the further piston surface is formed by an abutment piece having a recess receiving a shaped head of the slide and contacting said spring.
 12. A device according to claim 11, wherein said further slide extends through the shaped head of the slide and has a blind axial bore communicating with at least one radial bore extending through the peripheral surface of the further slide and with said bore via the interior of the slide.
 13. A device according to claim 11, wherein the further slide has a shaped head engaging in a recess of a further abutment piece contacted by the spring associated with the further slide.
 14. A device according to claim 9, and further comprising a non-return valve locating in a bore communicating with said chamber, said non-return valve serving to allow fluid to flow outwardly from the chamber when the working chamber of the prop is relieved and the pressure in the bore falls. 